Couplers are well-known devices to interconnect hoses or tubes in a fluid flow system. A coupler typically includes a coupler socket (female element) and a nipple (male element). The coupler socket is attached by a first hose or tube to a source of fluid, e.g., a compressed air source, while the nipple is attached by a second hose or tube to e.g., a tool or machine. When the nipple is inserted into the coupler socket, a closure valve mounted within the socket opens to provide a fluid flow path through the coupler. At the same time, a catch or coupling mechanism automatically engages the nipple to retain the nipple within the socket. The coupling mechanism can be selectively manually released to disconnect the nipple from the coupler socket. Such a coupler is typically referred to as a "push-to-connect" coupler.
In certain segments of the industry, the configuration of the nipple for pressurized air lines is fairly standard. For example, in the pressurized air industry, the IS0 6150 Series B nipple (i.e., the "industrial interchange" nipple) is generally accepted in the United States for air hose couplers. The Series B nipple includes a tubular shank or plug circumscribing a central bore and a downstream port which enables the nipple to be connected to an air hose or tube. The shank of the nipple narrows down at its inlet end and a circumferential, slightly rounded ridge is formed about the midpoint of this narrow portion. A groove or channel is defined between the ridge and the remainder of the shank. When the nipple is inserted into the socket, the coupling mechanism is received in the groove and engages the ridge on the shank to retain the nipple within the coupler socket.
A number of different types of coupler sockets have been developed for retaining the Series B type of nipple within the coupler. One popular type of coupler socket provides an venting function before the nipple is fully disconnected. This venting function allows pressurized air (or other fluid) within the coupler to be exhausted from the coupler socket before the nipple is entirely disconnected.
An example of this type of coupler socket is shown in Palau, et al., U.S. Pat. No. 4,483,510. The Palau coupler socket moves the nipple to an intermediate position for venting pressure within the coupler before the nipple is entirely released. A spring-biased tubular lock element (i.e., a "push button") is mounted for radial movement on the coupler body. A single tooth is provided on one inner side of the push button and projects radially inward, while a pair of teeth are provided on the diametrically opposite inner side of the push button and project radially inward from the opposite direction. The teeth are designed to engage the ridge on the nipple in two successive inward displacements of the push button. The first displacement allows the nipple to move into an intermediate venting position, while the second displacement releases the nipple and allows the nipple to be fully disconnected. French Patent No. 2 511 115 shows a similar coupler wherein an upper push button is initially pushed radially inward to allow the nipple to move to an intermediate venting position, and then a lower push button is pushed radially inward to allow the nipple to be fully released and removed from the coupler socket.
Blauenstein, U.S. Pat. No. 4,366,945, Moberg, U.S. Pat. No. 4,546,956 and Heilmann, U.S. Pat. No. 5,290,009, also show couplers which allow the nipple to move to an intermediate venting position before the nipple is fully released from the coupler socket. The Heilmann and Moberg patents have an axially movable outer cover or sleeve which allows the coupling mechanism to be selectively released. The coupling mechanism retains the nipple within the socket until the pressure within the nipple is reduced to atmospheric pressure. The coupling mechanism then automatically releases the nipple to allow the nipple to be disconnected from the socket. Blauenstein, on the other hand, has locking pins which initially engage and retain the nipple within the socket, and then as an outer cover or sleeve is moved axially, has locking balls which engage and retain the nipple in an intermediate position. The outer cover is again manipulated to fully release the nipple.
German, U.S. Pat. No. 3,434,063 and French Patent No. 2 527 741, also show a similar venting function for the coupler, however, the nipple is not disclosed as being moved to an intermediate position in these references. Rather, German retains the nipple in the locked position and rotates an internal valve, while French 2 527 741 moves an outer sleeve to seal off the air passages within the coupler and then the vents the pressure within the nipple. Both of these patents disclose outer, axially movable covers or sleeves which are manipulated to release the nipple.
While the above-described couplers provide a venting function prior to fully disconnecting the nipple, they are not without drawbacks. Some of the known couplers can be difficult or expensive to manufacture and assemble, particularly when the coupling components are designed for radial movement, or where there are numerous moving parts. Other of the known couplers can be complicated to operate, and require either a combination of rotation and axial sleeve movements, or the operation of two sleeves to provide the connect, venting and disconnect function. Other couplers can be prone to malfunction when contaminants (dirt, oil, etc.) infiltrate the moving parts of the coupler. Still other couplers, particularly those which have an intermediate venting position, are only operable with IS0 6150 Series C type nipples. These types of nipples have a sharp, outwardly-projecting shoulder on the ridge of the nipple to facilitate retaining the nipple within the coupler socket. These types of nipples are not prevalent in the United States, and so the couplers for these nipples do not have widespread applicability to the United States market.
Thus, it is believed that there is a demand in the industry for a push-to-connect type coupler with an intermediate venting function which i) is reliable, ii) is easy to operate, iii) is relatively simple and inexpensive to manufacture and assemble, and iv) can be used with ISO 6150 Series B type nipples which are widely available in the United States.